WASHINGTON — President Bush unveiled a $7.1 billion plan Tuesday to guard against an avian flu pandemic, proposing to stockpile 20 million doses of vaccine, speed up research and hone state and local preparations for such a sweeping health emergency.

Key to preparations: better early warning systems to detect and contain novel influenza strains before they reach the nation’s shores and overhauling the vaccine industry so every American eventually could be inoculated within six months of a pandemic’s beginning.

The ambitious vaccine change will take years to implement — Bush’s goal is 2010 — and his plan drew immediate fire from critics who said it does not provide enough protection in the meantime. States, too, got an unpleasant surprise, ordered to purchase millions of doses of an anti-flu drug with their own money. But Bush said cities, states and countries will all have to do their fair share to survive a worldwide outbreak of the worrisome Asian bird flu or some other super-strain of influenza.

“Every nation, every state in this union and every community in these states must be ready,” Bush said in a speech Tuesday.

Pandemics strike when the easy-to-mutate influenza virus shifts to a strain that people have never experienced before, something that has happened three times in the last century.

While it is impossible to say when the next super-flu will strike, concern is growing that the bird flu strain known as H5N1 could trigger one if it mutates to start spreading easily among people. Since 2003, at least 62 people in Southeast Asia have died from H5N1 and most of the victims regularly handled poultry.

Bush’s strategy includes $1.2billion to stockpile enough vaccine against the current H5N1 flu strain to protect 20million Americans, the estimated number of health workers and other first-responders involved in a pandemic; $1billion for the drugs Tamiflu and Relenza, which can treat and, in some cases, prevent flu infection; $2.8billion to create ways to manufacture flu vaccines in easier-to-handle cell cultures, instead of today’s slow method that relies on millions of chicken eggs; and a call for Congress to provide liability protection for makers of a pandemic vaccine.

Public health specialists, briefed on the strategy but awaiting details, called it a good start.

“Clearly this is the No.1 public health issue on the radar screen,” said Michael Osterholm of the University of Minnesota, who advises the government on infectious disease threats.

House Minority Leader Nancy Pelosi, D-San Francisco, criticized Bush’s plan as not doing enough to help state and local governments prepare for a potential pandemic and not giving enough protection to citizens who may become ill from vaccines.

The states’ collective tab would reach $510million, said Kim Elliott, deputy director of the nonpartisan Trust for America’s Health. She worried that some wouldn’t buy any, and that others wouldn’t share their Tamiflu stash if a pandemic struck in a part of the country that ran out.

Kevin Reilly, deputy director of prevention services at the California Department of Health Services, said it’s too soon to say whether states will be adequately supported by the federal government.

If a pandemic strikes, the Department of Health and Human Services will direct the medical response, and today it will unveil long-awaited details. Still to be finalized is a plan from the Homeland Security Department, which will coordinate how the government balances protecting the public with keeping schools, businesses and transportation sectors running.

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